Each encoder requires two free IO lines and since the signals can trigger relatively quick it is preferred that at least one of the inputs is an interrupt.The TinyQED is an ATTiny45 based widget that counts the signals from the encoders and makes them available via I2C. The counts can than easily be read from an Arduino using the Wiring library.

I was wondering if it should be possible to apply two of these boards parallel from each other. I have made this with one set of 10k pull-up resistors and it doesn’t work immediately. When I touch the SDA and SCL lines many times it suddenly start working.. Regards, Nick